1. Field of the Invention
The embodiments of the present invention relate generally to a filter housing assembly for exhaust applications and leak testing thereof.
2. Background of the Invention
Cleanrooms are utilized in many industries for contamination control and to improve product yields. A plurality of filters, typically mounted in the ceiling of the cleanroom, are configured to remove particulates from air entering and/or exhausted the cleanroom at a predetermined efficiency selected based upon the cleanliness requirements of the activities performed in the cleanroom. As particulates load the filtration media disposed in the filter, the airflow through the filter decreases as the pressure drop across the filter increases. Once the filter reaches a critical pressure drop, the filter is typically replaced.
On other applications, replacement of filters is scheduled based on time or processes performed within the cleanroom. For example, in many pharmaceutical and biotech cleanrooms, periodic replacement of filters is required to meet regulatory or owner specifications. To facilitate efficient replacement of the filter, a ducted supply hood is typically mounted in the cleanroom ceiling in which the filter may be readily removed and replaced from the cleanroom side of the ceiling.
In many applications, the installed replacement filter must be leak tested before normal cleanroom activities may commence. In order to perform a statistically valid leak test within a reasonable time period, an aerosol challenge is introduced into the hood upstream of the filter. However, in filters used in exhaust applications, the downstream side of the filter is above the cleanroom ceiling, and is often not accessible. Moreover, introducing aerosol within the cleanroom to challenge a filter is also undesirable.
Therefore, there is a need for a ducted hood, i.e., a housing assembly, and a technique to facilitate testing of filters used in exhaust applications.